Inductance control system

ABSTRACT

An example polarity inverter includes multiple contactors, each of which includes switches that are controllable to configure a current path. Each of the multiple contactors includes contacts, which are interleaved such that first contacts to receive voltage having a first polarity alternate with second contacts to receive voltage having a second polarity, where the first polarity and the second polarity are different. The polarity inverter also includes a first conductive plate to connect electrically to each of the first contacts, and a second conductive plate to connect electrically to each of the second contacts. The first conductive plate and the second conductive plate are in parallel. A dielectric material is between the first conductive plate and the second conductive plate.

TECHNICAL FIELD

This specification describes examples techniques for controllinginductance in an electronic component, such as a polarity inverter.

BACKGROUND

An example polarity inverter includes circuitry to change the polarityof an electrical signal, such as voltage or current. Polarity, ingeneral, represents electrical potential in a circuit. According toconvention, current flows from a positive-polarity terminal to anegative-polarity terminal. Physically, however, electrons flow from thenegative-polarity terminal to the positive-polarity terminal. Thepositive-polarity terminal has greater electrical potential than thenegative-polarity terminal. Accordingly, polarity can be understood interms of both current and voltage.

Inductance includes the tendency of an electrical conductor to oppose achange in current flowing therethrough. Inductance therefore can affectoperation of devices, such as a polarity inverter, that implementchanges in current.

SUMMARY

An example polarity inverter includes multiple contactors. Each of themultiple contactors includes switches that are controllable to configurea current path. Each of the multiple contactors also includes contacts,which are interleaved such that first contacts to receive voltage havinga first polarity alternate with second contacts to receive voltagehaving a second polarity, where the first polarity and the secondpolarity are different. The polarity inverter also includes a firstconductive plate to connect electrically to each of the first contacts,and a second conductive plate to connect electrically to each of thesecond contacts. The first conductive plate and the second conductiveplate are in parallel. A dielectric material is between the firstconductive plate and the second conductive plate. The polarity invertermay include one or more of the following features, either alone or incombination.

A number of the contactors may correspond to an amount of current topass through the polarity inverter and may be a based on specificationsfor a type of contactor used. The contacts may include input contacts.Each of the multiple contactors may include output contacts on differentsides of the switches than the input contacts. The output contacts maybe interleaved such that third contacts on a current path with the firstcontacts alternate with fourth contacts on a current path with thesecond contacts. The polarity inverter may also include a first bus barto connect electrically to each of the third contacts, a second bus barto connect electrically to each of the fourth contacts, where the firstbus bar and the second bus bar are in parallel, and a dielectricmaterial between the first bus bar and the second bus bar.

The switches may be controllable to configure current to flow in a firstdirection or in a second direction through the multiple contactors. Thefirst direction may be opposite to the second direction. Each of thefirst conductive plate and the second conductive plate may includeconductive fingers to connect to respective ones of the contacts. Themultiple contactors may include at least two input contactors and atleast two output contactors. The at least two input contactors may beconfigured to receive current from a current source and the at least twooutput contactors may be configured to output current on a path to adevice interface board. The dielectric may be or include a polyimidefilm. The dielectric may be or include polypropylene.

Spacing between the first plate and the second plate and interleaving ofthe contacts may enable the polarity inverter to have an inductance thatis less than 200 nanohenries (nH). Spacing between the first plate andthe second plate and interleaving of the contacts may enable thepolarity inverter to have an inductance that is 100 nanohenries (nH) orless.

A thickness of the dielectric material between the first plate and thesecond plate may be on the order of tenths of a millimeter. A thicknessof the dielectric material between the first plate and the second platemay be 0.5 millimeters (mm) or less. A thickness of the dielectricmaterial between the first bus bar and the second bus bar may be on theorder of tenths of a millimeter. A thickness of the dielectric materialbetween the first bus bar and the second bus bar may be 0.5 millimeters(mm) or less.

The contactors may include input contactors and output contactors. Theinput contactors may include the first conductive plate and the secondconductive plate connected, respectively to a first voltage or currentand to a second voltage or current. The polarity inverter may includeoutput contactors having contacts that are interleaved such that thirdcontacts that receive voltage or current having the first polarityalternate with fourth contacts that receive voltage or current havingthe second polarity. The polarity inverter may also include a thirdconductive plate to connect electrically to each of the third contacts,and a fourth conductive plate to connect electrically to each of thefourth contacts, where the third conductive plate and the fourthconductive plate are in parallel. The first polarity may be a positivevoltage with respect to the second polarity. The first polarity may be aforce-high voltage and the second polarity may be a force-low voltage,where the force-high voltage is greater than the force-low voltage.

An example test system includes a device interface board (DIB) toconnect to devices under test (DUTs), an interposer to connect to theDIB, a current source, and a polarity inverter to receive current fromthe current source and to control a directional flow of the currentrelative to the interposer. The polarity inverter includes multiplecontactors, each of which includes switches that are controllable toconfigure a current path. Each of the multiple contactors includescontacts, which are interleaved such that first contacts to receivevoltage having a first polarity alternate with second contacts toreceive voltage having a second polarity, where the first polarity andthe second polarity are different. The polarity inverter also includes afirst conductive plate to connect electrically to each of the firstcontacts, and a second conductive plate to connect electrically to eachof the second contacts. The first conductive plate and the secondconductive plate are in parallel. A dielectric material is between thefirst conductive plate and the second conductive plate. The example testsystem may include one or more of the following features, either aloneor in combination.

The switches may be controllable to configure current to flow in a firstdirection or a second direction through the multiple contactors. Thefirst direction may be reverse to the second direction. The polarityinverter may include at least two input contactors and at least twooutput contactors. The at least two input contactors may be configuredto receive the current from the current source and the at least twooutput contactors may be configured to output the current to theinterposer.

Any two or more of the features described in this specification,including in this summary section, may be combined to formimplementations not specifically described in this specification.

At least part of the devices and techniques described in thisspecification may be configured or controlled by executing, on one ormore processing devices, instructions that are stored on one or morenon-transitory machine-readable storage media. Examples ofnon-transitory machine-readable storage media include read-only memory,an optical disk drive, memory disk drive, and random access memory. Atleast part of the devices and techniques described in this specificationmay be configured or controlled using a computing system comprised ofone or more processing devices and memory storing instructions that areexecutable by the one or more processing devices to perform variouscontrol operations including high-current testing. The devices, systems,and/or components described herein may be configured, for examplethrough design, construction, arrangement, placement, programming,operation, activation, deactivation, and/or control.

The details of one or more implementations are set forth in theaccompanying drawings and the following description. Other features andadvantages will be apparent from the description and drawings, and fromthe claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of components of an example polarity inverter.

FIG. 2 is a diagram showing a right perspective view of an examplepolarity inverter configured for reductions in inductance.

FIG. 3 is a left perspective view of the example polarity inverter ofFIG. 2 .

FIG. 4 is a perspective view of example conductive parallel plates thatare attachable to the polarity inverters described herein.

FIG. 5 is a perspective view of example conductive parallel bus barsthat are attachable to the polarity inverters described herein.

FIG. 6 is a block diagram of an example system that includes the examplepolarity inverter.

Like reference numerals in different figures indicate like elements.

DETAILED DESCRIPTION

Described herein are examples of techniques for reducing inductance inelectronic devices, such as a polarity inverter. In an example, apolarity inverter is configured to reduce or to minimize the inductancearound the polarity inverter, thereby reducing the total inductance ofat least part of a signal delivery path between a source of current anddestination of the current, such as device under test (DUT). In anexample, the polarity inverter includes multiple contactors, each ofwhich includes switches that are controllable to configure a currentpath. Each of the contactors includes contacts that are interleaved suchthat first contacts to receive voltage having a first polarity alternatewith second contacts to receive voltage having a second polarity that isdifferent from the first polarity. A first conductive plate isconfigured to connect electrically to each of the first contacts, and asecond conductive plate is configured to connect electrically to each ofthe second contacts. The first conductive plate and the secondconductive plate are physically arranged to be in parallel, and adielectric material is between the first conductive plate and the secondconductive plate. The current path is therefore defined, in part, by theconductive plates and switches.

By using parallel plates of the type described herein, particularlyplates that are close together, the overall inductance of the polarityinverter can be reduced. For example, the overall inductance of thepolarity inverter can be minimized or reduced relative to prior polarityinverters having different configurations. In addition, alternating thefirst and second contacts may cancel and, therefore, at least partlyreduce the overall inductance. Furthermore, as described below, parallelbus bars separated by dielectric may also be part of the current path.In an example, there may be one set of parallel bus bars on each side ofthe polarity inverter. By using bus bars of this type, particularly busbars that are close together, the overall inductance of the polarityinverter can be further reduced. In an example, the inductance measuredon a high-current (e.g., 2000 Amperes (A)), low-inductance polarityinverter of the type described herein is about 100 nanoHenries (nH)compared to about 480 nH in an example prior polarity inverter. Thatbeing said, the polarity inverters described herein are not limited tothese, or to any, specific inductance values, current values, and/orvoltage values.

FIG. 1 shows a block diagram of components included in an examplepolarity inverter 10. In this example, polarity inverter 10 includes sixcontactors 11 to 16. An example contactor is an electronic device thatincludes switches and other circuitry to route current from its inputcontacts to its output contacts. Referring to contactor 13, which isrepresentative of the other contactors, each contactor includes fourinput contacts labeled collectively as 18 and four output contactslabeled collectively as 19. However, the techniques described herein arenot limited to contactors having this configuration. Switches (notshown) reside within each contactor to control the current paths betweenthe input contacts and the output contacts. The switches may becontrolled electronically or manually. For example a computing system orcontroller (see FIG. 6 , for example) may control individual switches toopen or to close to configure or to create desired current path(s)through the polarity inverter.

In an example operation, a current source is connected in series withpolarity inverter 10, as shown in FIG. 6 . In this example, the currentsource is a high-current source. Examples of high current include, butare not limited to, currents over 500 A, over 1000 A, over 2000 A, over3000 A, and so forth. In some implementations, the current is pulsed atleast part of the time or all of the time. In some example, a pulsedcurrent includes a rapid, transient change in amplitude from a baselinevalue such as “0” to a higher or lower value, followed by a rapid returnto the baseline value. In some implementations, the current is periodic,for example, sinusoidal. In some implementations, the current issteady-state at least part of the time. The current source is connectedin series with the input terminals of the polarity inverter to provide apositive polarity, e.g., force-high voltage/current (or simply,“force-high), at input terminal 20 and to provide a negative polarity,e.g., force-low voltage/current (or simply, “force-low”), at inputterminal 21. A device, such as a device interface board (DIB) of a testsystem (see FIG. 6 ) is connected in series with the output terminals ofthe polarity inverter to selectively provide a positive polarity, e.g.,force-high voltage/current, or a negative polarity, e.g., force-lowvoltage/current, at output terminals 24 and 25. In this example, outputterminals 24 and 25 are labeled “collector” and “emitter” to representthe input voltage and output voltage terminals of a bipolar junctiontransistor (BJT); however, more generally, terminals 24 and 25 may beany terminals configured to provide different-polarity electricalsignals to a connected device or system. In some examples, voltageswithin a range of 35 Volts (V) to 85V may be used; however, the systemsdescribed herein are not limited to any voltage range.

In this example, contactors 12, 13, 15, and 16 are configured as inputsand contactors 11 and 14 are configured as outputs or loads. Forexample, input voltage and current is applied to input contactors 12,13, 15, and 16 and that voltage and current is output to outputcontactors 11 and 14 and, from there, to terminals 24 and 25 as shown inFIG. 1 . The contacts on each of the contactors are interleaved suchthat a first set of contacts that receive voltage and current having afirst polarity, such as force-high or positive, alternate with a secondset of contacts that receive voltage and current having a secondpolarity, such as force-low or negative. Alternating the contacts inthis manner on each of the contactors alternates the current pathsthrough the contactors and may reduce inductance, as described herein.

By way of example, for contactor 13, contacts {circle around (1)} andare connected to force-high and contacts {circle around (3)} and {circlearound (7)} are connected to force-low. Also, contacts {circle around(2)} and {circle around (6)} are connectable along a same current pathas contacts {circle around (1)} and {circle around (5)}, whereascontacts {circle around (4)} and {circle around (8)} are connectablealong a same current path as contacts {circle around (3)} and {circlearound (7)}. Contacts {circle around (1)}, {circle around (3)}, {circlearound (5)}, and {circle around (7)} are interleaved in the sense thatno two adjacent contacts are connected to a same polarity voltage andcurrent. The same is true for contacts {circle around (2)}, {circlearound (4)}, {circle around (6)}, and {circle around (8)}. Statedanother way, the contacts are interleaved in the sense that theyalternate in polarity. In an example, on the input side 26 of contactor13, contact {circle around (1)} is connected to force-high, contact{circle around (3)} is connected to force-low, contact {circle around(5)} is connected to force-high, and contact {circle around (7)} isconnected to force-low. In an example, on the output side 27 ofcontactor 13, contact {circle around (2)} is connectable to force-high,contact {circle around (4)} is connectable to force-low, contact {circlearound (6)} is connectable to force-high, and contact {circle around(8)} is connectable to force-low. Each of input contactors 12, 15, and16 has the same contact configuration of input and output contacts asinput contactor 13, which is shown in FIG. 1 .

By way of example, for output contactor 11, contacts {circle around (1)}and {circle around (5)} are connected to terminal 24 and contacts{circle around (3)} and {circle around (7)} are connected to terminal25. Also, contacts {circle around (2)} and {circle around (6)} areconnectable along a same current path as contacts {circle around (1)}and {circle around (5)}, whereas contacts {circle around (4)} and{circle around (8)} are connectable along a same current path ascontacts {circle around (3)} and {circle around (7)}. Contacts {circlearound (1)}, {circle around (3)}, {circle around (5)}, and {circlearound (7)} are interleaved in the sense that no two adjacent contactsare connected to a same polarity voltage and current. The same is truefor contacts {circle around (2)}, {circle around (4)}, {circle around(6)}, and {circle around (8)}. Stated another way, the contacts areinterleaved in the sense that they alternate in polarity. In an example,on the input side 34 of contactor 11, contact {circle around (1)} isconnected to terminal 24, contact {circle around (3)} is connected toterminal 25, contact {circle around (5)} is connected to terminal 24,and contact {circle around (7)} is connected to terminal 25. In anexample, on the output side 27 of contactor 11, contact {circle around(2)} is connectable to force-high, contact {circle around (4)} isconnectable to force-low, contact {circle around (6)} is connectable toforce-high, and contact {circle around (8)} is connectable to force-low.Contactor 14 has the same contact configuration of input and outputcontacts as contactor 11. In addition, “input” 34 and “output” 35 on theoutput contactors are labeled according to convention and do notnecessarily note directions of current flow into or out of the outputcontactors.

In an example operation, switches within the contactors arecontrolled—for example controlled to open or to close—to provideforce-high to terminal 24 (e.g., a collector) and to provide force-lowto terminal 25 (e.g., an emitter).

To provide force-high to terminal 24, switches in input contactors 30are controlled—for example closed—so that current paths are createdbetween contacts {circle around (1)} and {circle around (2)} and betweencontacts {circle around (5)} and {circle around (6)}. Switches in outputcontactor 11 are controlled—for example closed—so that current paths arecreated between contacts {circle around (1)} and {circle around (2)} andbetween contacts {circle around (5)} and {circle around (6)}. Switcheswithin contactors 30 are controlled—for example opened—to preventcurrent flow to or from contacts {circle around (3)} and {circle around(4)} and to or from {circle around (7)} and {circle around (8)}.Switches within output contactor 11 are controlled—for example opened—toprevent current flow to or from contacts {circle around (3)}, {circlearound (4)}, {circle around (7)}, and {circle around (8)}.

To provide force-low to terminal 25, switches in input contactors 31 arecontrolled—for example closed—so that current paths are created betweencontacts {circle around (3)} and {circle around (4)} and betweencontacts {circle around (7)} and {circle around (8)}. Switches in outputcontactor 14 are controlled—for example closed—so that current paths arecreated between contacts {circle around (3)} and {circle around (4)} andbetween contacts {circle around (7)} and {circle around (8)}. Switcheswithin contactors 31 are controlled—for example opened—to preventcurrent flow to or from contacts {circle around (1)} and {circle around(2)} and to or from {circle around (5)} and {circle around (6)}.Switches within contactor 14 are controlled—for example opened—toprevent current flow to or from contacts {circle around (1)}, {circlearound (2)}, {circle around (5)}, and {circle around (6)}.

In a different example operation, switches within the contactors arecontrolled—for example controlled to open or to close—to provideforce-high to terminal 25 (e.g., an emitter) and to provide force-low toterminal 24 (e.g., a collector). This reverses the polarity of theoutput terminals 24 and 25, and thus reverses the current direction,relative to the configuration described in the preceding paragraphs.

To provide force-high to terminal 25, switches in input contactors 31are controlled—for example closed—so that current paths are createdbetween contacts {circle around (1)} and {circle around (2)} and betweencontacts {circle around (5)} and {circle around (6)}. Switches in outputcontactor 14 are controlled—for example closed—so that current paths arecreated between contacts {circle around (1)} and {circle around (2)} andbetween contacts {circle around (5)} and {circle around (6)}. Switcheswithin contactors 31 are controlled—for example opened—to preventcurrent flow to or from contacts {circle around (3)} and {circle around(4)} and to or from {circle around (7)} and {circle around (8)}.Switches within output contactor 14 are controlled—for example opened—toprevent current flow to or from contacts {circle around (3)}, {circlearound (4)}, {circle around (7)}, and {circle around (8)}.

To provide force-low to terminal 24, switches in input contactors 30 arecontrolled—for example closed—so that current paths are created betweencontacts {circle around (3)} and {circle around (4)} and betweencontacts {circle around (7)} and {circle around (8)}. Switches in outputcontactor 11 are controlled—for example closed—so that current paths arecreated between contacts {circle around (3)} and {circle around (4)} andbetween contacts {circle around (7)} and {circle around (8)}. Switcheswithin contactors 30 are controlled—for example opened—to preventcurrent flow to or from contacts {circle around (1)} and {circle around(2)} and to or from {circle around (5)} and {circle around (6)}.Switches within contactor 11 are controlled—for example opened—toprevent current flow to or from contacts {circle around (1)}, {circlearound (2)}, {circle around (5)}, and {circle around (6)}.

The preceding paragraphs describe examples of how current flow throughpolarity inverter 10 can be reversed by controlling operation of thecontactor switches. To reduce the overall inductance of the polarityinverter, the contacts and associated switches within the contactors areinterleaved as described previously. Also, electrical connections to theinput terminals and the output terminals of the polarity inverter may beimplemented using parallel conductive plates separated by an insulator.

Electrical Connections of the various input contacts, such as contacts{circle around (1)}, {circle around (3)}, {circle around (5)}, and{circle around (7)}, to force-high voltage/current and force-lowvoltage/current may be implemented using parallel conductive plates thatare separated by a dielectric material so that the conductive plates donot touch and create a current path. Electrical connections of thevarious output contacts, such as contacts {circle around (2)}, {circlearound (4)}, {circle around (6)}, and {circle around (8)}, may beimplemented using parallel conductive bus bars that are separated by adielectric material so that the conductive bus bars do not touch andcreate a current path. FIGS. 2 and 3 shows an example implementation ofa polarity inverter 40 containing contactors described with respect toFIG. 1 and also the conductive plates and conductive bus bars describedherein. FIG. 4 shows a perspective view of a pair of conductive plates41 that may be used with polarity inverter 40 and FIG. 5 shows aperspective view of a pair of conductive bus bars 42 that may be usedwith polarity inverter 40.

In the example polarity inverter 40, contactors 43 to 48 may have thesame structure and function as respective contactors 11 to 16 of FIG. 1. In polarity inverter 40, there are two sets of conductive plates 50and 51. The first set of conductive plates 51 is electrically connectedto input terminals such as terminals 20 and 21 of FIG. 1 and the secondset of conductive plates 50 is electrically connected to outputterminals such as terminal 24 and 25 of FIG. 1 . Conductive plates 51are in a current path that includes a current source, such as that shownin FIG. 6 . Conductive plates 50 are in a current path to an outputdevice such a DIB of a test system such as that shown in FIG. 6 .Conductive plates 50 and 51 are not directly electrically connected toeach, but rather connect electrically through the contactors asdescribed herein.

In this example, conductive plate 55 is connected to a positive polarityor force-high voltage/current and conductive plate 56 is connected to anegative polarity or force-low voltage/current. In this exampleconductive plate 57 is connected to one output terminal (e.g., theemitter of FIG. 1 ) and conductive plate 58 is connected to anotheroutput terminal (e.g., the collector of FIG. 1 ). The polarities of thecurrents and voltages on the conductive plates 55, 56, 57, and 58 arecontrolled by controlling the switches in the contactors as describedwith respect to FIG. 1 .

The input contacts on contactors 43 to 48 are connected to conductiveplates 50 and 51 as shown in FIG. 1 . The output contacts on contactors43 to 48 are connected to conductive bus bars 42 a, 42 b that arearranged in parallel as shown in FIG. 1 and that are separated by adielectric material. Referring to FIGS. 1, 2 and 3 , there may be oneset of parallel bus bars 42 a to implement electrical connections 61 onthe output side and one set of parallel bus bars 42 b to implementelectrical connections 60 on the output side. The conductive bus barsand conductive plates may be made of any appropriateelectrically-conductive material including, but not limited to, copperor gold. Examples of dielectrics that may be sandwiched between parallelconductive plates and parallel bus bars include, but are not limited to,Formex®, Kapton®, polyimide film, polypropylene, or a combinationthereof. In another example, the dielectric is mylar tape having athickness of 10 mils (0.254 mm).

In the examples of FIGS. 2 and 3 , polarity inverter 40 includes sixcontactors 42 to 48. In this example, each contactor includes contactsand, therefore, six contactors have 24 contacts on their collective top64 and 24 contacts on their collective bottom 65. For a given contactorsuch as contactor 43, two points of contact are force-highvoltage/current and the remaining two points of contact are force-lowvoltage/current. The conductive plates are made using parallel copperplates. The conductive plates 51 for the input contactors 44, 45, 47,and 48 are configured such that two fingers from top copper plate 55 arealternatively terminated into four contacts at force-highvoltage/current, force-low voltage/current, force-high voltage/currentand force-low voltage/current, and such that two fingers from bottomcopper plate 56 are alternatively terminated into four contacts atforce-high voltage/current, force-low voltage/current, force-highvoltage/current and force-low voltage/current. The conductive plates 50for the output contactors 43 and 46 are configured such that twonon-adjacent fingers of top copper plate 58 are terminated into twocontacts at force-high voltage/current and two non-adjacent fingers ofbottom copper plate 57 are terminated into two contacts at force-lowvoltage/current. This configuration may reduce inductance by increasingthe number of parallel current paths through the polarity inverter. Theoutput contacts of each contactor are connected via parallel bus bars inthe manner shown in FIG. 1 .

Reducing the spacing between the conductive plates may reduce theinductance associated with the plates and thereby reduce the inductanceof the overall polarity inverter. For example, a thickness of thedielectric material between any two parallel conductive plates may be onthe order of tenths of a millimeter (mm), such as 0.1 mm, 0.2 mm, 0.3mm, 0.4 mm. 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm. In someimplementations, the thickness of the dielectric material between anytwo parallel conductive plates may be 0.5 mm or less. Similarly,reducing the spacing between the parallel bus bars may reduce theinductance associated with the parallel bus bars and thereby reduce theoverall inductance of the polarity inverter. For example, a thickness ofthe dielectric material between any two parallel bus bars may be on theorder of tenths of a millimeter (mm), such as 0.1 mm, 0.2 mm, 0.3 mm,0.4 mm. 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm. In someimplementations, the thickness of the dielectric material between theparallel bus bars may be 0.5 mm or less.

In some implementations, the combination of features described herein,such as the bus bars and spacing therebetween, the conductive plates andspacing therebetween, and the interleaved contacts and switches, enablesthe polarity inverter to have an inductance that is less than 200nanohenries (nH) or that is less than 100 nH. That being said, one ormore of the features described herein may enable the polarity inverteror any appropriate electronic device containing those features to reduceits inductance to these levels or to levels that are higher or lowerthan these levels.

The polarity inverter described herein may be part of a test system thatincludes automatic test equipment ATE 70. For example, as shown in FIG.6 , an example test system may include a current source 71, a polarityinverter 72 of the type described herein (e.g. polarity inverter 10 ofFIG. 1 or polarity inverter 40 of FIGS. 2 and 3 ), an interposer 73, anda DIB 74. Current flows from the current source through the polarityinverter 72, where its polarity is either kept the same or changed asdescribed herein. Current output from the polarity inverter is passed tointerposer 73, which is an electrical and/or mechanical interface to DIB74. The DIB, as noted, holds DUTs in sites 75 for testing anddistributes the current from the interposer to the DUTs for testing.

ATE 70 also includes a control system 76. The control system may includea computing system comprised of one or more microprocessors or otherappropriate processing devices as described herein. Communicationbetween the control system and the other components of ATE 70 isrepresented conceptually by line 77. DIB 74 includes a printed circuitboard (PCB) that includes mechanical and electrical interfaces to one ormore DUTs that are being tested or are to be tested by the ATE. Power,including voltage, may be run via one or more layers in the DIB to DUTsconnected to the DIB. DIB 74 also may include one or more ground layersand one or signal layers with connected vias for transmitting signals tothe DUTs.

The DIB includes sites 75, which may include pins, conductive traces, orother points of electrical and mechanical connection to which the DUTsmay connect. Test signals and response signals, including high currentsignals pass via test channels over the sites between the DUTs and testinstruments. DIB 74 may also include, among other things, connectors,conductive traces, conductive layers, and circuitry for routing signalsbetween test instruments, DUTs connected to sites 75, and othercircuitry.

Control system 76 communicates with test instruments (not shown) tocontrol testing. Control system 76 may also configure the switcheswithin polarity inverter 72 to provide voltage/current at the polarityrequired for testing. The control may be adaptive in that the polaritymay be changed during testing if desired or required.

All or part of the test systems described in this specification andtheir various modifications may be configured or controlled at least inpart by one or more computers such as control system 76 using one ormore computer programs tangibly embodied in one or more informationcarriers, such as in one or more non-transitory machine-readable storagemedia. A computer program can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module,part, subroutine, or other unit suitable for use in a computingenvironment. A computer program can be deployed to be executed on onecomputer or on multiple computers at one site or distributed acrossmultiple sites and interconnected by a network.

Actions associated with configuring or controlling the test systemdescribed herein can be performed by one or more programmable processorsexecuting one or more computer programs to control or to perform all orsome of the operations described herein. All or part of the test systemsand processes can be configured or controlled by special purpose logiccircuitry, such as, an FPGA (field programmable gate array) and/or anASIC (application-specific integrated circuit) or embeddedmicroprocessor(s) localized to the instrument hardware.

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only storagearea or a random access storage area or both. Elements of a computerinclude one or more processors for executing instructions and one ormore storage area devices for storing instructions and data. Generally,a computer will also include, or be operatively coupled to receive datafrom, or transfer data to, or both, one or more machine-readable storagemedia, such as mass storage devices for storing data, such as magnetic,magneto-optical disks, or optical disks. Non-transitory machine-readablestorage media suitable for embodying computer program instructions anddata include all forms of non-volatile storage area, including by way ofexample, semiconductor storage area devices, such as EPROM (erasableprogrammable read-only memory), EEPROM (electrically erasableprogrammable read-only memory), and flash storage area devices; magneticdisks, such as internal hard disks or removable disks; magneto-opticaldisks; and CD-ROM (compact disc read-only memory) and DVD-ROM (digitalversatile disc read-only memory).

Elements of different implementations described may be combined to formother implementations not specifically set forth previously. Elementsmay be left out of the systems described previously without adverselyaffecting their operation or the operation of the system in general.Furthermore, various separate elements may be combined into one or moreindividual elements to perform the functions described in thisspecification.

Other implementations not specifically described in this specificationare also within the scope of the following claims.

What is claimed is:
 1. A polarity inverter comprising: multiplecontactors, each of the multiple contactors comprising switches that arecontrollable to configure a current path, each of the multiplecontactors comprising contacts, the contacts being interleaved such thatfirst contacts to receive voltage having a first polarity alternate withsecond contacts to receive voltage having a second polarity, the firstpolarity and the second polarity being different; a first conductiveplate to connect electrically to each of the first contacts; a secondconductive plate to connect electrically to each of the second contacts,the first conductive plate and the second conductive plate being inparallel; and a dielectric material between the first conductive plateand the second conductive plate.
 2. The polarity inverter of claim 1,wherein a number of the contactors corresponds to an amount of currentto pass through the polarity inverter and is a based on specificationsfor a type of contactor used.
 3. The polarity inverter of claim 1,wherein the contacts comprise input contacts; wherein each of themultiple contactors comprises output contacts on different sides of theswitches than the input contacts, the output contacts being interleavedsuch that third contacts on a current path with the first contactsalternate with fourth contacts on a current path with the secondcontacts; and wherein the polarity inverter comprises: a first bus barto connect electrically to each of the third contacts; a second bus barto connect electrically to each of the fourth contacts, the first busbar and the second bus bar being in parallel; and a dielectric materialbetween the first bus bar and the second bus bar.
 4. The polarityinverter of claim 1, wherein the switches are controllable to configurecurrent to flow in a first direction or in a second direction throughthe multiple contactors, the first direction being opposite to thesecond direction.
 5. The polarity inverter of claim 1, wherein the eachof the first conductive plate and the second conductive plate comprisesconductive fingers to connect to respective ones of the contacts.
 6. Thepolarity inverter of claim 1, wherein the multiple contactors compriseat least two input contactors and at least two output contactors, the atleast two input contactors being configured to receive current from acurrent source and the at least two output contactors being configuredto output current on a path to a device interface board.
 7. The polarityinverter of claim 1, wherein the dielectric material comprises apolyimide film.
 8. The polarity inverter of claim 1, wherein thedielectric material comprises polypropylene.
 9. The polarity inverter ofclaim 1, wherein spacing between the first conductive plate and thesecond conductive plate and interleaving of the contacts enables thepolarity inverter to have an inductance that is less than 200nanohenries (nH).
 10. The polarity inverter of claim 1, wherein spacingbetween the first conductive plate and the second conductive plate andinterleaving of the contacts enables the polarity inverter to have aninductance that is 100 nanohenries (nH) or less.
 11. The polarityinverter of claim 1, wherein a thickness of the dielectric materialbetween the first conductive plate and the second conductive plate is onthe order of tenths of a millimeter.
 12. The polarity inverter of claim1, wherein a thickness of the dielectric material between the firstconductive plate and the second conductive plate is 0.5 millimeters (mm)or less.
 13. The polarity inverter of claim 3, wherein a thickness ofthe dielectric material between the first bus bar and the second bus baris on the order of tenths of a millimeter.
 14. The polarity inverter ofclaim 3, wherein a thickness of the dielectric material between thefirst bus bar and the second bus bar is 0.5 millimeters (mm) or less.15. The polarity inverter of claim 1, wherein the contactors compriseinput contactors and output contactors, the input contactors comprisingthe first conductive plate and the second conductive plate connected,respectively to a first voltage and to a second voltage; and wherein thepolarity inverter comprises output contactors comprising contacts thatare interleaved such that third contacts that receive voltage having thefirst polarity alternate with fourth contacts that receive voltagehaving the second polarity; and wherein the polarity inverter comprises:a third conductive plate to connect electrically to each of the thirdcontacts; a fourth conductive plate to connect electrically to each ofthe fourth contacts, the third conductive plate and the fourthconductive plate being in parallel.
 16. The polarity inverter of claim1, wherein the first polarity is a positive voltage with respect to thesecond polarity.
 17. The polarity inverter of claim 1, wherein the firstpolarity is a force-high voltage and the second polarity is a force-lowvoltage, where the force-high voltage is greater than the force-lowvoltage.
 18. A test system comprising: a device interface board (DIB) toconnect to devices under test (DUTs); an interposer to connect to theDIB; a current source; and a polarity inverter to receive current fromthe current source and to control a directional flow of the currentrelative to the interposer; the polarity inverter comprising: multiplecontactors, each of the multiple contactors comprising switches that arecontrollable to configure a current path, each of the multiplecontactors comprising contacts, the contacts being interleaved such thatfirst contacts to receive voltage having a first polarity alternate withsecond contacts to receive voltage having a second polarity, the firstpolarity and the second polarity being different; a first conductiveplate to connect electrically to each of the first contacts; a secondconductive plate to connect electrically to each of the second contacts,the first conductive plate and the second conductive plate being inparallel; and a dielectric material between the first conductive plateand the second conductive plate.
 19. The polarity inverter of claim 18,wherein the switches are controllable to configure current to flow in afirst direction or a second direction through the multiple contactors,the first direction being reverse to the second direction.
 20. Thepolarity inverter of claim 18, wherein the polarity inverter comprisesat least two input contactors and at least two output contactors, the atleast two input contactors being configured to receive the current fromthe current source and the at least two output contactors beingconfigured to output the current to the interposer.